Catalyst and method for the dehydrogenation of ethylbenzene to styrene

 

(57) Abstract:

The invention relates to catalysts for dehydrogenation of ethylbenzene to styrene. The catalyst contains, as active components of iron oxide and a promoter selected from the oxides of alkali and alkaline earth metals, oxides lantanoides number and oxides of chromium, tungsten and molybdenum, and it is made in the form of specific granules of cylindrical shape having one or more through holes obtained by direct compression of powders predecessors and/or active components when using the grease applied to the wall of the molding die and the punches form. Also described is a method of dehydrogenation of ethylbenzene to styrene using a catalyst of the above composition. The technical result - the reduction of the pressure drop, which takes place in a reactor with a fixed layer, and improve the activity and selectivity of the catalyst. 2 S. and 6 C.p. f-crystals, 2 tab.

The present invention relates to catalysts in the form of hollow granules having a specific geometric shape and suitable for the dehydrogenation of telebasel in styrene.

The previous and the present patent application discloses catalysts available is rising with holes in different petals, obtained by direct compression (pelletizing) powder and die wall and punches cause the grease.

The obtained catalysts differ consistently sizes, high resistance to wear and fracture and a very narrow distribution of the pore radius.

Due to the aforementioned type of porosity and high relation between the geometric area and volume of particles catalysts can significantly reduce the pressure drop that takes place in a reactor with a fixed layer, and significantly improve the activity and selectivity of the catalyst.

In patent literature related to the catalytic dehydrogenation of telebasel in styrene, the interest is almost always aimed at improving and optimizing the chemical composition, in order to achieve more satisfactory performance. Improvements are usually achieved by varying the composition, mainly the main components, or by use of different promoters.

The geometry of the catalyst still has paid limited attention.

The importance of the form can be directly related to the pressure used in technological processes. P equilibrium towards products (styrene and hydrogen) with further improvement of the conversion. Thus, the desirable possibility of modification of the form of the catalyst, in order to carry out the process at a lower pressure (and consequently, to reduce the pressure drop in the catalyst bed).

In addition, the dehydrogenation reaction is performed in the presence of steam to reduce the partial pressure of styrene to shift the equilibrium towards the formation of styrene.

To resolve this problem we selected two modifications in the form:

1) the diameter of the granules was increased (to 5 mm) without changing its length. This solved the problem only to a very limited extent, because the pressure drop was indeed achieved by reducing the bulk density (and hence, by the total number of voids), however, the geometric surface, able to participate in catalysis, declined. The result of these two opposite effects were slow performance;

2) was introduced three - or five-petalled form. In this case, it was obtained a weak improvement. However, it should be borne in mind that the spider form has the disadvantage that the powder is more easily deformed because the petals have more weak points prone to fracture, sravnitel extrusion. It should be noted that this technologically simple process has a very important limitation: it is characteristic that it is not possible to obtain a complex geometric shape, in particular a hollow form.

With regard to the composition, the catalysts for dehydrogenation of ethylbenzene to styrene include iron oxide, oxides of alkali and alkaline earth metals and other oxides selected from the oxides of cerium, molybdenum, tungsten and chromium.

The service life of the catalysts can be increased by adding chromium oxide as a stabilizer. In U.S. patent N 3360597 disclosed catalysts, which contain 0.5-5% Cr2O3in addition to 80-90% Fe2O3and 9-18% K2CO3. The catalyst prepared in accordance with the method, which involves mixing in water yellow iron oxide, chromium oxide and potassium carbonate, to obtain a paste, from which the catalyst in the form of cylindrical pellets by extrusion, drying and calcination.

In U.S. patent N 5023225 disclosed a catalyst for dehydrogenation of ethylbenzene to styrene, which is based on iron oxide, the oxides of the alkaline or alkaline earth metals, and the oxides of cerium, molybdenum or tungsten, characterized the process of shaping differs that yellow iron oxide, mixed with chromium oxide, heated to 500-1000oC to convert in the red iron oxide before the components are mixed in the form of a wet paste. The forming is carried out by extrusion.

Catalysts for dehydrogenation of the present invention have a hollow geometric shape (with one or more through holes), obtained by pressing (tabletting) the way in which you want to use grease not distributed in the mass of powder to be formed (volumetric lubrication), and is applied to the walls of the molding dies and punches (external lubrication).

The resulting catalysts compared to the catalysts obtained using volumetric lubrication, have a higher porosity, a more narrow distribution of the pore radius and low macroporosity. Porosity is usually from 0.15 to 0.35 cm3/g (determined by absorption of mercury). The surface area is usually from 1 to 6 m3/g (determined by the BET-method (method of brunauer-Emmett-teller to determine the surface adsorbents isothermal adsorption)). Distribution curve porosity does not include the ones who sustained fashion, the average radius of the pores ranges from 800 to 1800 .

In addition, the catalysts have constant values of size parameters. The constant parameters size cannot be obtained using the processes of forming, using volumetric lubrication, due to the significant number of micro-cracks that appear on part or all of the catalytic particle, causing their fragility and subsequent deformation.

Because of these deformation processes of pressing in the matrix, which is applied volumetric lubrication, never used commercially for the production of hollow granular catalysts. In addition, it was found that the catalysts according to the present invention differ in mechanical properties, much higher, in particular, tensile strength under axial tension (in the direction of the axis of the hole) than the property of the respective catalysts, obtained using volumetric lubrication. The tensile strength in the axial direction is more than 15 H on the particle and the strength (in the direction of the axis of the holes) is much higher than the corresponding catalysts prepared using volumetric lubrication. The tensile strength in the axial direction extending t powder is typically less than 3%. The catalysts obtained by extrusion, typically have a resistance to wear from 4 to 8 wt%. The catalysts according to the present invention due to the fact that they are hollow, allow to achieve higher conversion at the same weight compared to catalysts in solid form.

In addition, a higher content of cavities characteristic of these catalysts can operate at equal volumetric flow rates with lower pressure than is required when using the catalysts integral form.

The higher content of cavities allows to operate at a higher ratio steam/ethylbenzene than usual when using catalysts having a solid form, thus obtaining a higher conversion rate with equal pressure during the process.

The weight ratio of steam/ethylbenzene used with the catalysts according to the invention, is more than 1.5 and can be 2.5 or more.

The presence of holes allows you to work with a smaller wall thickness than the catalysts solid form, and therefore it is better to use the weight of the catalyst. When such catalysts minimum wall thickness that can be achieved is from 0.6 to 0.8 mm

The pressure drop observed with a three-catalysts according to the invention, at least 1.3 times lower than when using the catalyst solid forms of the same geometric surface.

Lubricant, which can be used for preparation of catalysts according to the invention, including solid and liquid capable of reducing the coefficient of friction between the powder, which tabletroute, and parts of the tablet, which comes in contact with the said powder.

Examples of suitable lubricants are stearic and palmitic acids, salts of alkali and alkaline earth metals of these acids, such as stearates of magnesium and potassium, carbon black, talc, mono - and triglycerides, such as monostearate - glycerol and mono-oleate-glycerin, paraffin oil and parfocality.

Liquid lubricant can be used as a solution or as a dispersion system in the dispersant.

The amount of liquid lubricant typically ranges from 0.025 to 25 mg per granule.

Solid lubricants can be applied by the strokes, supplied continuously with a stream of air or other gases in order to achieve optimum dispersion of solid particles.

Forming the matrix and the punches can be made from self-lubricating materials or coated with these materials, such as PTFE or ceramic materials. This allows you to avoid or reduce the use of lubricants.

The catalysts according to the present invention preferably have a cylindrical shape with one or more through holes, the axes of which are essentially parallel to one another and relative to the axis of the granules and are essentially mutually ravnovesie.

Through holes preferably have a circular cross-section. In the case of the catalyst with three through-hole axis is formed in the cross section of the particle angle essentially an equilateral triangle; the corners are oriented relative to the points where the cross section is in contact with the described circle. The petals are mostly cylindrical and ring identical to one another and coaxially with the through holes.

Granules can be essentially triangular cross dtweedie axes) and the diameter of the above-mentioned holes is preferably from 1.15 to 1.5, and more preferably from 1.3 to 1.4.

The relationship between the height of the particles and the step of holes is preferably from 1.5 to 2.5, and more preferably from 1.7 to 2.3.

In the case of catalysts having a circular cross-section, the relationship between the radius of curvature of each petal and spacing of the holes is preferably from 0.6 to 0.9, more preferably from 0.7 to 0.8. The relationship between the radius of curvature of the petals and the radius of the through holes is preferably from 1.3 to 2.7, more preferably from 1.8 to 2.1. The relationship between the radius of a circle circumscribed around the cross-section, and the radius of curvature of the round petals is preferably from 1.6 to 2, more preferably between 1.7 and 1.85 to. The ratio of surface to volume of each pellet in the multi-leaf variant is preferably greater than 2.0, and more preferably more than 2,2.

In the case of catalysts having a triangular cross-section, the relationship between the radius of curvature of each rounded corner and spacing of the holes is preferably from 0.7 to 0.8. The relationship between the radius of the circle circumscribed around the cross-section, and the radius of curvature of each rounded corner is before Ianto, having a triangular cross-section, is preferably more than 2.0, more preferably more than 2.2.

In the preparation of the catalysts according to the present invention, the powder containing precursor and/or active components of the catalyst are mixed dry or kneaded with a small amount of water to obtain a mixture with a homogeneous distribution of components.

The resulting mixture is subjected to drying and/or stage of calcination at a temperature of from 120 to 1000oC for a time sufficient to remove water and volatile products of decomposition.

Commonly used pressure is more than 100 kg/cm2and can reach up to 1000 kg/cm2.

In addition, it was discovered, and it is introduced in the following aspect of the present invention that the catalysts with mechanical properties, especially tensile strength under axial tension, which are among the catalysts that can be obtained by molding with an external lubrication can be obtained by shaping using volumetric lubrication provided that the powder before giving the form is subjected to heat treatment, ways isout bulk grease in quantities of less than 5% weight.

The resulting powder suitable for the manufacture of granules of the desired size and shape using the method of pressing in the matrix.

After forming granules calicivirus at 600-900oC.

In the mass of granules or on their surface can be dispelled such promoters and stabilizers, as the oxides of calcium, magnesium, chromium, molybdenum and tungsten. For application to the surface of the desired components can be used a variety of methods. For example, a component or components can be sprayed on the granules during tableting after the stage of external lubrication.

In addition, you can use a lubricant that acts as a precursor of the desired compounds, such as alkaline stearates or alkaline earth metal.

After calcination, these compounds are converted to corresponding oxides or mixtures of oxides and salts.

You can use other mixtures of lubricants and oxides or other catalytically active compounds and spreading a thin layer on the surface of the granules during moulding.

As a variant, the granules of the catalyst can be coated with a thin film on the processing stage that is separate from the tabletting and which is paraut during heating to a temperature of 80-200oC solution or dispersion promoter and stabilizing oxides or salts of metals by means of a spray. The concentration of the dispersion, the contact time, the temperature at which the applied coating may change so as to ensure rapid and complete evaporation of water or other dispersing medium, to obtain a surface layer having the desired thickness, usually from 0.1 to 100 microns.

As for the final composition of oxides in a weight ratio of the catalysts include 50-92% of iron oxide, 5-20% alkali metal oxide, 0.5 to 14% of oxide of alkaline earth metal, 2-10% of the series of lanthanides, 0.5 to 6% of oxide of a metal of the sixth group of the periodic table.

Among the oxides of alkali metals, the preferred oxide of potassium, whereas among the oxides of alkaline earth metals are preferred oxides of magnesium and calcium. Of oxides of a number of preferred lanthanides cerium oxide, and the oxides of molybdenum and tungsten are preferred from the oxides of metals of group VI.

You can use, for example, iron hydroxide, nitrate or carbonate of iron, hydroxide or potassium carbonate, cerium carbonate or ammonium molybdate as precursors of active ingredients.

Typical>3= 78%, K2O = 12%, CeO2= 5%; MgO = 2%; WO3= 0,9%; MoO3= 2,1%

Another typical composition, again expressed in weight percent of oxides is:

Fe2O3= 74%;2O = 6%; CeO2= 10%; MgO = 4%, WO3= 6%.

Catalysts with heterogeneous composition obtained by surface deposition on the pellets promoter and a stabilizing component contains 40-95% of iron oxide, 5-30% alkali metal oxide, 0.5 to 4% of oxide of alkaline earth metal, about 0.1-10% of oxide of the element number of the lanthanides, 0.5 to 4% of chromium oxide, molybdenum or tungsten.

After iron oxide are preferred, in particular, potassium oxide, calcium oxide, magnesium oxide, cerium oxide and the oxides of chromium, molybdenum and tungsten.

Examples of preferred, but non-derogable compositions are listed in table. 1. Asterisks marked component, which can be applied to the surface.

The reaction of dehydrogenation of ethylbenzene to styrene is usually carried out at temperatures from 540 to 650oC and pressures above, below, or equal to atmospheric pressure. Low pressure are preferred for thermodynamic reasons, as they provide better env the law of invention.

Analytical determination

Tensile strength under axial elongation was determined in accordance with ASTM (American standard of testing materials) D 4179/82; apparent density (after utracki) was determined by ASTM D 4164/82.

Example comparison 1

The paste is prepared by mixing iron hydroxide, cerium carbonate, magnesium carbonate and oxide of tungsten with an aqueous solution of potassium hydroxide so as to obtain a finished catalyst having the following composition (expressed for oxides in weight percent).

Oxides, %;

Fe2O3- 76,1

K2O - 14,0

CeO2- 6,5

MgO - 2,5

WO3- 0,9

Pasta ekstragiruyut to obtain pellets with a length of 5 mm and a diameter of 3.5 mm Extruded pellets are dried at 150oC for 16 hours, and then calicivirus 400oC for 2 hours. A number of granules calicivirus at 700oC for 2 hours. These granules are the catalyst 1.

EXAMPLE 1

The second part of the granules prepared in accordance with example comparison 1, grind and powder tabletirujut, using as external lubricants stearic acid. The plug and the cylindrical chamber of tablature cover with a thin layer steare is within a diameter of 2 mm Use a pressure of 500 kg/cm2. Cylindrical pellets calicivirus at 700oC within 2 hours.

This catalyst is a catalyst No. 2. Tensile strength in axial extension of this catalyst is 13.4 H on the particle.

EXAMPLE 2

The second part of the granules prepared in accordance with example comparison 1, grind and tabletirujut (using stearic acid as external lubrication) in the form of a three-form with three parallel through-hole having an inner diameter of 1.3 mm, wall thickness 0.8 mm, the radius of curvature of 2.5 mm and a height of 5 mm Holes are in the corners of an equilateral triangle. Tablets calicivirus at 700oC within 2 hours.

This catalyst No. 3. Tensile strength in axial extension of this catalyst is to 20.9 H on the particle.

EXAMPLE 3

A catalyst having the following composition of oxides, expressed in weight percent, prepared by the method of example comparison 1:

Fe2O3= 74,5%;2O = 6,1%; CeO2= 9,6%; MgO = 4,0%; WO3= 5,8%.

Fe2O3in the red spheroidal form is used as Fe2O3. K2O is introduced as a CON.


Some of the granules prepared according to the method of example 2, in order to obtain a three-granules with three holes that has the characteristics specified in example 2.

Instead of stearic acid using magnesium stearate as an external lubrication.

Tensile strength in axial extension of this catalyst was 32 H on the particle; 38% of the volume occupied by pores having a radius of from 600 to 800 , 11% of the pores having a radius of from 800 to 1000 , 12% of the pores having a radius of from 1000 to 2000 and 6% of the pores having a radius of from 2000 to 4000 .

Macroporosity with a radius of more than 50,000 was absent here.

The surface area of the catalyst is 4.9 m2/g; porosity of 0.17 ml/year

This catalyst No. 5.

EXAMPLE 5

Catalysts No. 1, 2, 3, 4 and 5 have in a steel reactor with an inner diameter of 35 mm In each test the reactor was placed 200 cm3catalyst and placed on a steel grate. Tests carried out at 570o, 590oand 610oC for each of the catalyst; in these tests the water vapor and ethylbenzene, pre-heated to the above temperature, is passed through the catalyst bed at a water/ethyl benzene 2,4-weight; - press the options take more than 2 hours after as the system is stabilized for at least 20 hours in each mode. The degree of conversion and the molar selectivity, expressed in percentages, are listed in table. 2.

1. The catalyst for the dehydrogenation of ethylbenzene to styrene, comprising as active components of iron oxide and a promoter selected from the oxides of alkali and alkaline earth metals, oxides lantanoides number and oxides of chromium, tungsten and molybdenum, characterized in that it is made in the form of specific granules of cylindrical shape having one or more through holes obtained by direct compression of powders predecessors and/or active components when using the grease applied to the wall of the molding die and the punches form.

2. The catalyst p. 1, characterized in that it has a porosity of from 0.15 to 0.35 cm3/g and on the basis of the curve of distribution of the porosity is more than 50% of pores with a radius of more than 600 and does not contain macropores with a radius of more than 50,000 .

3. The catalyst PP.1 and 2, characterized in that it has the form of cylindrical granules with one or more through hole, the axes of which are parallel to each other and to the axis of the granules.

4. The catalyst p. 3, SS="ptx2">

5. The catalyst p. 4, characterized in that it has three holes for which the ratio between the pitch of holes and diameter of the above-mentioned holes is from 1.15 to 1.5, and the ratio between the height of the granules and spacing of the holes ranges from 1.5 to 2.5.

6. The catalyst PP.1 to 4, characterized in that it has the form of a multi-leaf granules, the axis of the petals which are coaxial with the axes of the through holes and for which the ratio between the pitch and diameter of the holes ranges from 1.15 to 1.5, and the ratio between the height of the granules and spacing of the holes ranges from 1.5 to 2.5.

7. The method of dehydrogenation of ethylbenzene to styrene, wherein the used catalyst PP.1 - 6.

8. The method according to p. 7, characterized in that the weight ratio of steam/ethylbenzene used in the dehydrogenation of ethylbenzene, is more than 1.5.

 

Same patents:

The invention relates to a method for the dehydrogenation of alkylaromatic hydrocarbons, in particular to a method for dehydrogenation of ethylbenzene to obtain styrene, and can be used in the petrochemical industry
The invention relates to the petrochemical industry and can be used in the process of joint production of propylene oxide and styrene
The invention relates to the petrochemical industry and can be used in the process for the joint production of propylene oxide and styrene

The invention relates to the petrochemical industry and can be used in the production of styrene by dehydrogenation of ethylbenzene and dehydration of methylphenylcarbinol

The invention relates to the petrochemical industry and can be used in the process for the joint production of propylene oxide and styrene

The invention relates to a method for producing styrene by digitala methylphenylcarbinol fraction containing up to 3 wt.% heavy residues produced in the production process of propylene oxide and styrene, in the presence of water vapor on the catalyst containing alumina, and the process is carried out by adding to the original methylphenylcarbinol fraction of water vapor and hydrogen-containing gas mass ratio of methylphenylcarbinol : water vapor : hydrogen, equal 1: 0,03 - 0,6 : 0,0004 - 0,001, and heating in a single stream to the reaction temperature before entering the catalytic zone
The invention relates to catalytic processes, in particular the obtaining of styrene by the catalytic dehydrogenas ethylbenzene on iron oxide catalysts at a temperature of 560 - 640oC in the presence of water vapor, followed by separation of styrene from the products of dehydrogenation of ethylbenzene (furnace oil) by multistage distillation with sequential allocation benzatropine faction, return ethylbenzene and styrene-rectified

The invention relates to the petrochemical industry and can be used to obtain styrene by dehydration of methylphenylcarbinol during the joint production of propylene oxide and styrene

The invention relates to a catalyst used in the methods of hydroconversion hydrocarbons, which contain small amounts of metals

The invention relates to high-strength porous systems and concerns of the catalyst precursor or membrane, or catalytic membrane system, and method of production thereof

The invention relates to the reaction of steam reforming of dimethyl ether in order to obtain hydrogen-rich gas mixture which can be used in hydrogen energy, in particular, as a fuel for fuel cells for various applications, including fuel cells installed on mobile media

The invention relates to a method for prevodioca by low-temperature conversion of orthovalerate, to the composition of the catalyst to obtain and to a method for producing this catalyst

The invention relates to catalysts for the refining and petrochemicals used in the process for hydrogenation refining of crude desalted oil and method of its preparation
Up!